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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Thermal momentum in thermodynamics and interfacial electrification

Get access (open in a dialog) DOI: 10.1615/IHTC12.4050
6 pages

Résumé

In his fundamental work on the Brownian motion, Einstein introduced into thermodynamics a concept that plays a central role in Newtonian mechanics: the time-rate of change of momentum, which is associated with the thermal motion of particles dissolved or suspended in a liquid. Einstein's treatment, however, was not concerned with the transport through the liquid surface.This paper appliessome consequences of this author's generalization to interfacialsystems of Einstein's theory. A basic result is obtained: whenever certain thermodynamic parameters are different across a surface, a membrane, or any other interface, the first and second laws collectively require the existence of electric charges at such sites. This nearly universal property of interfaces confirms Newton's conception in the 18th Century of the electric nature of forces of capillarity, cohesion, and attraction between macroscopic particles. Further corroboration of the theory has been provided by recently reported direct observations of some interfacial phenomena, including the separation of charges during frost growth.This interesting, thermodynamically-predictable, interfacial electrification property explains other phenomena of interdisciplinary interest, including: surface tension, drop coalescence, nucleation, fog and cloud suspension, and the separation of electric charges upon phase change, to mention a few examples.